Greenhouse gas emission of sugarcane irrigated with treated domestic sewage by subsurface drip in Southeast Brazil1

Reducing greenhouse gas emissions, reclaiming water for irrigation, and obtaining high agricultural yields are among the main agricultural challenges; therefore, this study aimed to analyse greenhouse gas emissions, including carbon dioxide, nitrous oxide, and methane emissions, in sugarcane irrigated with treated domestic sewage and with surface water, both with and without nutritional supplementation via fertigation, and in a nonirrigated control. Regarding the nonirrigated control with topdressing fertilization, nitrogen fertilization carried out by sewage or mineral sources decreased N-N2O emissions by nearly 38% and 66%, respectively. C-CH4 influx was found in all treatments with a nonsignificant contribution to the total emissions, representing average values between treatments near -54.56 g C-CH4 ha(-1). The crop irrigated with treated domestic sewage plus N minerals shows significantly the highest C-CO2 equivalent emissions (15.12 Mg CO2eq ha(-1)), and the treatment irrigated with sewage without N minerals showed the highest relation between the yield of theoretical recoverable sugar and C-CO2 equivalent emissions (2.63 Mg recoverable sugar Mg-1 CO2eq ha(-1)). The treatments using sewage or with surface water irrigation, both fertigated, increased the stalk biomass and sugar yield, with a higher yield of theoretical recoverable sugar.